1. Field of the Invention
The present invention relates generally to anatomical teaching models, and more particularly to an anatomical teaching model that illustrates a simulated abdominal wall.
2. Background
A hernia is an abnormal protrusion of an organ, tissue, or any anatomical structure through a forced opening in some part of the surrounding muscle wall. A hernia is formed by a weakening of the musculofascial tissues defining the structural wall of a body cavity such as the abdomen, resulting in a gap through which tissues can protrude. Typically, a sac is formed confining the tissues at the musculofascial defect, which sac protrudes from the plane of the tissue wall.
A weakening or separation of the musculofascial tissues due to any cause can develop into a hernia. For example scarring from a previous incision or other trauma of the abdominal wall can develop into a hernia, or a hernia can form at the site of a passage through the musculofascial tissue, the passage becoming enlarged, for example, due to pressure of the viscera during muscular exertion. There are various forms of hernias, the inguinal hernia being a common example wherein the abdominal viscera and peritoneal sac protrude through the floor of the inguinal cavity at the point where the musculofascial tissue is relatively weakened due to the passage of the spermatic duct (in males) or the femoral blood vessels and the round ligament (in females). Another common site of a hernia is the passage of the umbilical cord. Hernias can also develop in the diaphragm, and elsewhere. In general, similar problems occur wherever visceral tissues are abutted against a confining wall of tissue that, when weakened for whatever reason, permits the tissues to protrude through the confining wall. For example, if a part of the intestine were to protrude through the surrounding abdominal wall, it would create a hernia—an abdominal hernia.
Hernias occur in both males and females in the groin area, also called the inguinal region. In both sexes, the abdominal wall may be weak on both right and left sides a little above the crease in the groin. If a part of the intestines or other tissue within the abdominal cavity pushes through one of the weak spots, it forms a hernia—an inguinal hernia.
Before the piece of intestine or other abdominal cavity tissue, called the hernial mass, makes its way through the weak spot in the muscle, it must first push its way through the peritoneum, the membrane that lines the abdomen.
Inguinal hernias can be indirect space inguinal hernias or direct space inguinal hernias. An indirect space inguinal hernia occurs in the following manner. The lower part of the abdominal wall where such hernias occur, the inguinal region, is comprised of two layers, an inner layer, and an outer layer. Each layer has a weak spot in it but the weak spots are not directly aligned with each other. The weak spots in each layer are positioned slightly apart from each other.
In the medical field, it is necessary for students, doctors, and surgeons to be able to practice surgical and clinical techniques. More particularly, there is the need to practice the making of incisions, the removal or repair of various kinds of complaint (such as cysts and hernias, for example), access to structures below the epidermis and the insertion of sutures. As an alternative to providing an actual body or part of an actual body for practicing such techniques, there is a need for artificial means whereby they can be practiced.
Prospective surgical patients must be provided with adequate, easily understandable information regarding any surgical procedure, prior to the surgery, in order to grant their “informed consent” to the procedure. Patients must be apprised of traditional anterior abdominal surgical approaches, as well as, laparoscopic methods. In addition, the inclusion of prosthetic meshes, and the like, as a part of the surgical repair must be accurately and effectively described to the patient. Physicians have had few options to turn to for support in their efforts to provide a patient with easily understood explanations of these complex (at least to the patient) surgical procedures.
A variety of teaching methods are used in the biological and medical arts studies. One method of teaching the subject matter has been the development of three-dimensional models that allow students to better visualize the interrelationship between organs and tissues in a patient's body, as well as components of individual organs or structural components. Typically, these models are used to describe major organs, or organ systems. In particular, models have been developed to illustrate major systems such as the gastrointestinal tract. They typically provide a three-dimensional model that students can use to better understand the digestive system.
Known structures providing simulations of body tissue suffer from the disadvantage that they are not sufficiently analogous, either visually or physically, to actual body tissue.
One such simulated structure is described in U.S. Pat. No. 4,481,001 to Graham et al. discloses a human skin model for training/demonstration purposes. The model is a composite of several layers to simulate subcutaneous tissue and a dermis-simulating layer that has a slightly greater hardness than the subcutaneous tissue-simulating layer. An epidermis-simulating layer is made of a high tear strength, high tensile strength elastomer. One or more of the layers may be contoured so that the surface of the model is shaped to simulate contour defects in natural skin.
Another example of a training model of the prior art is described in U.S. Pat. No. 6,336,812 to Cooper et al., which discloses a training apparatus providing a simulation of at least part of a body and simulations of internal body structures for a particular part of the anatomy and being of increasing anatomical complexity and/or presenting increasing clinical or surgical difficulty.
U.S. Pat. No. 5,908,302 to Goldfarb describes a model for simulating inguinal hernias including a frame and a plurality of sheets supported by the frame in overlapping relation to one another to create an anatomically accurate simulation of a portion of a patient's abdomen. Each of the sheets includes predefined openings. One or more balloons are used to simulate a hernial sac. Anatomically correct overlays may be placed in overlapping relation to the front and back of the frame to show a patient the relative placement of other anatomical structures relative to the position of the hernia.
It would be desirable to provide a physical/mechanical model that simulates skin, tissue, and organs associated with abdominal wall morphology and pathology.